docs: add CONFIGURATION sections that map to a built-in

Add a CONFIGURATION section to the documentation of various built-ins,
for those cases where the relevant config/NAME.txt describes
configuration that is only used by the relevant built-in documented in
git-NAME.txt. Subsequent commits will handle more complex cases.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
index e1f48c9..5225f67 100644
--- a/Documentation/git-commit-graph.txt
+++ b/Documentation/git-commit-graph.txt
@@ -142,6 +142,13 @@
 $ git rev-parse HEAD | git commit-graph write --stdin-commits --append
 ------------------------------------------------
 
+CONFIGURATION
+-------------
+
+include::includes/cmd-config-section-all.txt[]
+
+include::config/commitgraph.txt[]
+
 
 GIT
 ---